1. Field of the Invention
The present invention relates to a method of and an apparatus for purifying exhaust gases of an internal combustion engine by employing a manifold reactor.
2. Description of the Prior Art
In an internal combustion engine, particularly a rotary piston engine, the exhaust gases of the engine are usually introduced into a manifold reactor provided in connection with exhaust ports of the engine, wherein secondary air is supplied to the exhaust gases to burn combustible gases such as CO, HC, etc, contained in the exhaust gases in the manifold reactor to effect purification of the exhaust gases. In this case, the secondary air is conventionally supplied to the exhaust gases delivered from the combustion chambers of the engine before they enter into the manifold reactor so that the combustible components contained in the exhaust gases have sufficient contact with oxygen supplemented with the secondary air for a time sufficient to accomplish perfect combustion of the combustible components while the exhaust gases flow through the manifold reactor. This conventional system of supplying the secondary air operates satisfactorily to accomplish the purification of the exhaust gases when the engine is in normal condition after the engine has been warmed up. However, in the cold starting up condition wherein the temperature of the exhaust gases has not yet been sufficiently raised and the manifold reactor is still relatively cold, if all of a predetermined amount of the secondary air has been supplied or ejected at a time into the exhaust gases delivered from the exhaust port, the temperature of the exhaust gases is lowered so far that perfect combustion of the combustible components is impeded and the performance of purifying the exhaust gas is deteriorated. Furthermore, even after the engine has been warmed up, the temperature of the exhaust gases substantially lowers when the engine is accelerated when compared with the normal operating condition and, accordingly, it causes an abrupt lowering of the exhaust gas temperature when all of the secondary air is supplied at one time to the exhaust gases delivered from the exhaust ports, resulting in prohibiting the perfect combustion of the exhaust gases.